Boron nitride containing hydroxyl groups efficiently catalysed oxidative dehydrogenation of ethane to ethylene,offering rather high selectivity（95%） but only small amount of CO2 formation（0.4%） at a given ethane c...Boron nitride containing hydroxyl groups efficiently catalysed oxidative dehydrogenation of ethane to ethylene,offering rather high selectivity（95%） but only small amount of CO2 formation（0.4%） at a given ethane conversion of 11%.Even at high conversion level of 63%,the selectivity of ethylene retained at 80%,which is competitive with the energy-demanding industrialized steam cracking route.A long-term test for 200 h resulted in stable conversion and product selectivity,showing the excellent catalytic stability.Both experimental and computational studies have identified that the hydrogen abstraction of B-OH groups by molecular oxygen dynamically generated the active sites and triggered ethane dehydrogenation.展开更多
The bioassay was directed to the fractionation of the methanol extract of the rhizomes of Zingiber officinale Roscoe leading to the isolation of a new antioxidant cyclic diarylheptanoid. The structure of the new compo...The bioassay was directed to the fractionation of the methanol extract of the rhizomes of Zingiber officinale Roscoe leading to the isolation of a new antioxidant cyclic diarylheptanoid. The structure of the new compound was established as 1, 5-epoxy-3-hydroxy-1-(3,4-dihydroxy-5-methoxy-phenyl)-7-(3,4-dihydroxyphenyl) heptane (1) on the basis of MS, 1D and 2D-NMR experiments.展开更多
Efficient conversion of lignin to fine chemicals and biofuel become more and more attractive in biorefinery. In this work, we used a series of silica-alumina catalysts （i.e., SiO2-Al2O3, HY, Hβ, and HZSM-5） to degr...Efficient conversion of lignin to fine chemicals and biofuel become more and more attractive in biorefinery. In this work, we used a series of silica-alumina catalysts （i.e., SiO2-Al2O3, HY, Hβ, and HZSM-5） to degrade lignin into arenes and phenols. The relationship between the catalyst structure and lignin depolymerization performance was investigated. The results showed that both acidity and pore size of the catalyst could influence the conversion of lignin. In the volatilizable product, phenols were identified as the main phenolic monomers via gas chromatography-mass spectrometer. SIO2-Al2O3 was the most efficient catalyst, giving 90.96% degree of conversion, 12.91% yield of phenols, and 2.41% yield of arenes in ethanol at 280℃ for 4 h. The Fourier transform infrared spectroscopy and ^1H nuclear magnetic resonance spectroscopy analysis demonstrated that deoxygenation and alkylation occurred in this process. The effect of solvents was also investigated and the results showed that ethanol was the most efficient solvent.展开更多
A promising Co3O4/Cu O composite electrode material was successfully synthesized through a facile hydrothermal and calcination process. Effects of the surfactants hexadecyltrimethyl ammonium bromide（CTAB） and polyvi...A promising Co3O4/Cu O composite electrode material was successfully synthesized through a facile hydrothermal and calcination process. Effects of the surfactants hexadecyltrimethyl ammonium bromide（CTAB） and polyvinylpyrrolidone（PVP） on the morphology and electrochemical performance of the composite were investigated. Powder X-ray diffraction（XRD）, scanning electron microscopy（SEM）, transmission electron microscopy（TEM） and nitrogen adsorption-desorption experiment were employed to characterize the microstructures and morphologies of the composite. Meanwhile, the electrochemical performances of the samples were studied using cyclic voltammetry（CV）, galvanostatic charge-discharge test and electrochemical impedance spectroscopy（EIS）. The results show that the porous Co3O4/Cu O-CTAB nanoplates own the best performance and exhibits a high specific capacitance of 398 F/g at 1 A/g with almost 100% capacitance retention over 2000 cycles, and it retains 90% of capacitance at 10 A/g.展开更多
Ag‐Cu‐Cl/BaCO3 catalysts with different Cl and Cu loadings, prepared by the reduction deposition impregnation method, were investigated for gas‐phase epoxidation of propylene by molecular oxygen and characterized b...Ag‐Cu‐Cl/BaCO3 catalysts with different Cl and Cu loadings, prepared by the reduction deposition impregnation method, were investigated for gas‐phase epoxidation of propylene by molecular oxygen and characterized by X‐ray diffraction, X‐ray photoelectron spectroscopy and O2 temperatureprogrammed desorption. Ag‐Cu‐Cl/BaCO3 catalyst with 0.036 wt% Cu and 0.060 wt% Cl exhibitedthe highest catalytic performance for gas‐phase epoxidation of propylene by molecular oxygen. Apropylene oxide selectivity of 83.7% and propylene conversion of 1.2% were achieved under thereaction conditions of 20% C3H6‐10% O2‐70% N2, 200 °C, 0.1 MPa and 3000 h?1. Increasing the Clloading allowed Ag to ensemble easier, whereas changing the Cu loading showed little effect on Agcrystallite size. The appropriate Cl loading of Ag‐Cu‐Cl/BaCO3 catalyst can reduce the dissociationadsorption of oxygen to atomic oxygen species leading to the combustion of propylene to CO2, whichbenefits epoxidation of propylene by molecular oxygen. Excessive Cl loading of Ag‐Cu‐Cl/BaCO3catalyst decreases propylene conversion and propylene oxide selectivity remarkably because of Clpoisoning. The appropriate Cu loading of Ag‐Cu‐Cl/BaCO3 catalyst is efficient for the epoxidation ofpropylene by molecular oxygen, and an excess Cu loading decreases propylene oxide selectivitybecause the aggregation of Cu species increases the exposed surfaces of Ag nanoparticles, whichwas shown by slight increases in atomic oxygen species adsorbed. The appropriate loadings of Cu and Cl of Ag‐Cu‐Cl/BaCO3 catalyst are important to strike the balance between molecular oxygen and atomic oxygen species to create a favorable epoxidation of propylene by molecular oxygen.展开更多
In the present work, we reported a novel route for the conversion of lignocellulosic biomass （sawdust） to a high-value chemical of benzoic acid under atmospheric pressure. The trans- formation involved the catalytic...In the present work, we reported a novel route for the conversion of lignocellulosic biomass （sawdust） to a high-value chemical of benzoic acid under atmospheric pressure. The trans- formation involved the catalytic pyrolysis of sawdust into aromatics, the decomposition of heavier alkylaromatics to toluene, and the liquid-phase oxidation of toluene-rich aromatics to benzoic acid. The production of the desired benzoic acid from the sawdust-derived aro- matics, with the benzoic acid selectivity of 85.1 C-mol% and nearly complete conversion of toluene, was achieved using the MnO2/NHPI catalyst at 100 ℃ for 5 h. The in uence of adding methanol on the catalytic conversion of sawdust to the core intermediate of toluene was also investigated in detail.展开更多
Cationic ring opening polymerization of octamethylcyclotetrasiloxane （Da） initiated by acid treated bentonite was investigated. The experimental conditions were chosen on the basis of preliminary experiments.Higher ...Cationic ring opening polymerization of octamethylcyclotetrasiloxane （Da） initiated by acid treated bentonite was investigated. The experimental conditions were chosen on the basis of preliminary experiments.Higher temperature was found beneficial for the reaction process while stirring intensity beyond a certain level showed no obvious effect on the reaction rate. Polymers were characterized by Fourier transform infrared, proton nuclear magnetic resonance （IH-NMR） and gel perneation chromotography. The width of molecular mass distribution was found ranging between 1.2 and 1.4, which is extraordinarlly narrow compared with that of cationic polymerizations reported elsewhere （〉 1.9）. The results were believed due to the absence of free proton and counter ion which simplifies the polymerization process and the huge steric hindrance provided by bentonite particles which keeps the propagation of polysiloxane onto the surface of bentonite particles in a much more regular way. A feasible mechanism is proposed and seems to be supported well by experiments. Additionally, from the results of α, ω-dihydrogen terminated polysiloxanes prepared, the possibility of applying this potential environmentally friendly heterogeneous catalyst in industrial polymerization of cyclosiloxanes is anticipated.展开更多
Oxidative dehydrogenation of light alkanes to alkenes is an attractive alternative route for industrial direct dehydrogenation because of favorable thermodynamic and kinetic characteristics,but encounters difficulties...Oxidative dehydrogenation of light alkanes to alkenes is an attractive alternative route for industrial direct dehydrogenation because of favorable thermodynamic and kinetic characteristics,but encounters difficulties in selectivity control for alkenes because of over-oxidation reactions that produce a substantial amount of undesired carbon oxides.Recent progress has revealed that boron nitride is a highly promising catalyst in the oxidative dehydrogenation of light alkanes because of its superior selectivity for and high productivity of light alkenes,negligible formation of CO2,and remarkable catalyst stability.From this viewpoint,recent works on boron nitride in the oxidative dehydrogenations of ethane,propane,butane,and ethylbenzene are reviewed,and the emphasis of this viewpoint is placed on discussing the catalytic origin of boron nitride in oxidative dehydrogenation reactions.After analyzing recent progress in the use of boron nitride for oxidative dehydrogenation reactions and finding much new evidence,we conclude that pure boron nitride is catalytically inert,and an activation period is required under the reaction conditions;this process is accompanied by an oxygen functionalization at the edge of boron nitride;the B-O species themselves have no catalytic activity in C-H cleavage,and the B-OH groups,with the assistance of molecular oxygen,play the key role in triggering the oxidative dehydrogenation of propane;the dissociative adsorption of molecular oxygen is involved in the reaction process;and a straightforward strategy for preparing an active boron nitride catalyst with hydroxyl groups at the edges can efficiently enhance the catalytic efficacy.A new redox reaction cycle based on the B-OH sites is also proposed.Furthermore,as this is a novel catalytic system,there is an urgent need to develop new methods to optimize the catalytic performances,clarify the catalytic function of boron species in the alkane ODH reactions,and disclose the reaction mechanism under realistic reaction conditions.展开更多
A series of hexadecylphosphate acid(HDPA) terminated mixed-oxide nanoparticles have been investigated to catalyze the oxidation of toluene exclusive to benzaldehyde under mild conditions in an emulsion of toluene/wate...A series of hexadecylphosphate acid(HDPA) terminated mixed-oxide nanoparticles have been investigated to catalyze the oxidation of toluene exclusive to benzaldehyde under mild conditions in an emulsion of toluene/water with the catalysts as stabilizers. With the HDPA-Fe2 O3/Al2 O3 as the basic catalyst, a series of transition metals, such as Mn, Co, Ni, Cu, Cr, Mo, V, and Ti, was respectively doped to the basic catalyst to modify the performance of the catalytic system, in expectation of influencing the mobility of the lattice oxygen species in the oxide catalysts. Under normally working conditions of the catalytic system, the nanoparticles of catalysts located themselves at the interface between the oil and water phases, constituting the Pickering emulsion. Both the doped iron oxide and its surface adsorbed hexadecylphosphate molecules were essential to the catalytic system for excellent performances with high toluene conversions as well as the exclusive selectivity to benzaldehyde. Under optimal conditions, ~83% of toluene conversion and >99% selectivity to benzaldehyde were obtained, using molecular oxygen as oxidant and HDPA-(Fe2 O3-Ni O)/Al2 O3 as the catalyst. This process is green and low cost to produce high quality benzaldehyde from O2 oxidation of toluene.展开更多
Transformation of lignin into high-value chemicals is hampered by the complexity of monomers obtained from lignin depolymerization. Here we report a strategy, composed of hy-dro-demethoxylation and de-alkylation react...Transformation of lignin into high-value chemicals is hampered by the complexity of monomers obtained from lignin depolymerization. Here we report a strategy, composed of hy-dro-demethoxylation and de-alkylation reactions, that is able to chemically converge various lig-nin-derived phenolic monomers into phenol in a single-step. Using 2-methoxy-4-propylphenol as a model compound, Pt/C exhibited the best performance in hydro-demethoxylation reaction afford-ing 80% 4-propylphenol from 2-methoxy-4-propylphenol, while H-ZSM-5 was identified as the most suitable catalyst for de-alkylation, achieving 83% yield of phenol from 4-propylphenol. Since the two catalysts operate under compatible conditions, combining the two catalysts to simultane-ously promote both hydro-demethoxylation and de-alkylation reactions was achieved. Configura-tion of how to organize the catalysts is a critical parameter, where the physical mixture of the two was most effective, providing over 60% phenol from 2-methoxy-4-propylphenol in a single-step.展开更多
A series of novel cobalt carbonyl ionic liquids based on1,1,3,3‐tetra‐alkyl‐guanidine,such as[1,1‐dimethyl‐3,3‐diethylguanidinium][Co(CO)4](3a),[1,1‐dimethyl‐3,3‐dibutylguanidinium][Co(CO)4](3b),[1,1‐dimethy...A series of novel cobalt carbonyl ionic liquids based on1,1,3,3‐tetra‐alkyl‐guanidine,such as[1,1‐dimethyl‐3,3‐diethylguanidinium][Co(CO)4](3a),[1,1‐dimethyl‐3,3‐dibutylguanidinium][Co(CO)4](3b),[1,1‐dimethyl‐3,3‐tetramethyleneguanidinium][Co(CO)4](3c),and[1,1‐dimethyl‐3,3‐pentamethyleneguanidinium][Co(CO)4](3d),were synthesized in good yields and were also characterized using infrared spectroscopy,ultraviolet‐visible spectroscopy,1H nuclear magnetic resonance(NMR)spectroscopy,13C NMR spectroscopy,high‐resolution mass spectrometry,differential scanning calorimetry,and thermogravimetric analysis.The four compounds exhibited high thermal and chemical stability.In addition,the catalytic performance of these compounds was investigated in the carbonylation of epoxides,with3a exhibiting the best catalytic activity without the aid of a base as the additive.The catalyst could be reused at least six times without significant decreases of the selectivity or conversion rate.Moreover,the catalyst system exhibited good tolerance with terminal epoxides bearing alkyl,alkenyl,aryl,alkoxy,and chloromethyl functional groups.展开更多
A modified solution-diffusion model was established based on Flory-Huggins thermodynamic theory and Fujita's free volume theory. This model was used for description of the mass transfer of removal benzene from dil...A modified solution-diffusion model was established based on Flory-Huggins thermodynamic theory and Fujita's free volume theory. This model was used for description of the mass transfer of removal benzene from dilute aqueous solutions through polydimethylsiloxane (PDMS) membranes. The effect of component concentration on the interaction parameter between components, that of the polymer membrane on the selectivity to benzene, and that of feed concentration and temperature on the permeation flux and separation factor of benzene/water through PDMS membranes were investigated. Calculated pervaporation fluxes of benzene and water were compared with the experimental results and were in good agreement with the experimental data.展开更多
AIM： To evaluate the hepatoprotective roles of （Z）- 5-（4-methoxybenzylidene）thiazolidine-2,4-dione （SKLB010） against carbon tetrachloride （CCI4）-induced acute and chronic liver injury and its underlying mecha...AIM： To evaluate the hepatoprotective roles of （Z）- 5-（4-methoxybenzylidene）thiazolidine-2,4-dione （SKLB010） against carbon tetrachloride （CCI4）-induced acute and chronic liver injury and its underlying mecha- nisms of action.展开更多
基金Project supported by the Sailing Plan of Maoming Green Chemical Industry Research Institute(No.MMGCIRI-2022YFJH-Y-037)the Science and Technology Planning Project of Maoming City(No.2022031)the Special Projects in Key Fields of Ordinary Universities of Guangdong Province(No.2020ZDZX2054)。
文摘以间甲氧基苯酚为原料,通过氧烷基化及Vilsmeier-Hack(V-H)反应合成了4-苄氧基-2-甲氧基苯甲醛,总收率为82.26%.最佳反应条件为:以四丁基溴化铵为催化剂,合成间苄氧基苯甲醚的反应时间为3 h,n(间苄氧基苯甲醚)∶n(DMF)∶n(POCl3)=1∶1.5∶2,V-H反应温度为70—75℃,生成V-H试剂时间为1.5 h,保温反应时间为3 h.
基金supported by the National Natural Science Foundation of China (21225312, U1462120, 21473206)Cheung Kong Scholars Programme of China (T2015036)~~
文摘Boron nitride containing hydroxyl groups efficiently catalysed oxidative dehydrogenation of ethane to ethylene,offering rather high selectivity（95%） but only small amount of CO2 formation（0.4%） at a given ethane conversion of 11%.Even at high conversion level of 63%,the selectivity of ethylene retained at 80%,which is competitive with the energy-demanding industrialized steam cracking route.A long-term test for 200 h resulted in stable conversion and product selectivity,showing the excellent catalytic stability.Both experimental and computational studies have identified that the hydrogen abstraction of B-OH groups by molecular oxygen dynamically generated the active sites and triggered ethane dehydrogenation.
文摘The bioassay was directed to the fractionation of the methanol extract of the rhizomes of Zingiber officinale Roscoe leading to the isolation of a new antioxidant cyclic diarylheptanoid. The structure of the new compound was established as 1, 5-epoxy-3-hydroxy-1-(3,4-dihydroxy-5-methoxy-phenyl)-7-(3,4-dihydroxyphenyl) heptane (1) on the basis of MS, 1D and 2D-NMR experiments.
文摘Efficient conversion of lignin to fine chemicals and biofuel become more and more attractive in biorefinery. In this work, we used a series of silica-alumina catalysts （i.e., SiO2-Al2O3, HY, Hβ, and HZSM-5） to degrade lignin into arenes and phenols. The relationship between the catalyst structure and lignin depolymerization performance was investigated. The results showed that both acidity and pore size of the catalyst could influence the conversion of lignin. In the volatilizable product, phenols were identified as the main phenolic monomers via gas chromatography-mass spectrometer. SIO2-Al2O3 was the most efficient catalyst, giving 90.96% degree of conversion, 12.91% yield of phenols, and 2.41% yield of arenes in ethanol at 280℃ for 4 h. The Fourier transform infrared spectroscopy and ^1H nuclear magnetic resonance spectroscopy analysis demonstrated that deoxygenation and alkylation occurred in this process. The effect of solvents was also investigated and the results showed that ethanol was the most efficient solvent.
基金Project(21471162)supported by the National Natural Science Foundation of ChinaProject(2014LY36)supported by the Science and Technology Project of Longyan CityChina
文摘A promising Co3O4/Cu O composite electrode material was successfully synthesized through a facile hydrothermal and calcination process. Effects of the surfactants hexadecyltrimethyl ammonium bromide（CTAB） and polyvinylpyrrolidone（PVP） on the morphology and electrochemical performance of the composite were investigated. Powder X-ray diffraction（XRD）, scanning electron microscopy（SEM）, transmission electron microscopy（TEM） and nitrogen adsorption-desorption experiment were employed to characterize the microstructures and morphologies of the composite. Meanwhile, the electrochemical performances of the samples were studied using cyclic voltammetry（CV）, galvanostatic charge-discharge test and electrochemical impedance spectroscopy（EIS）. The results show that the porous Co3O4/Cu O-CTAB nanoplates own the best performance and exhibits a high specific capacitance of 398 F/g at 1 A/g with almost 100% capacitance retention over 2000 cycles, and it retains 90% of capacitance at 10 A/g.
基金supported by National Basic Research Program of China (2013CB933200)Commission of Science and Technology of Shanghai Municipality (15DZ1205305)~~
文摘Ag‐Cu‐Cl/BaCO3 catalysts with different Cl and Cu loadings, prepared by the reduction deposition impregnation method, were investigated for gas‐phase epoxidation of propylene by molecular oxygen and characterized by X‐ray diffraction, X‐ray photoelectron spectroscopy and O2 temperatureprogrammed desorption. Ag‐Cu‐Cl/BaCO3 catalyst with 0.036 wt% Cu and 0.060 wt% Cl exhibitedthe highest catalytic performance for gas‐phase epoxidation of propylene by molecular oxygen. Apropylene oxide selectivity of 83.7% and propylene conversion of 1.2% were achieved under thereaction conditions of 20% C3H6‐10% O2‐70% N2, 200 °C, 0.1 MPa and 3000 h?1. Increasing the Clloading allowed Ag to ensemble easier, whereas changing the Cu loading showed little effect on Agcrystallite size. The appropriate Cl loading of Ag‐Cu‐Cl/BaCO3 catalyst can reduce the dissociationadsorption of oxygen to atomic oxygen species leading to the combustion of propylene to CO2, whichbenefits epoxidation of propylene by molecular oxygen. Excessive Cl loading of Ag‐Cu‐Cl/BaCO3catalyst decreases propylene conversion and propylene oxide selectivity remarkably because of Clpoisoning. The appropriate Cu loading of Ag‐Cu‐Cl/BaCO3 catalyst is efficient for the epoxidation ofpropylene by molecular oxygen, and an excess Cu loading decreases propylene oxide selectivitybecause the aggregation of Cu species increases the exposed surfaces of Ag nanoparticles, whichwas shown by slight increases in atomic oxygen species adsorbed. The appropriate loadings of Cu and Cl of Ag‐Cu‐Cl/BaCO3 catalyst are important to strike the balance between molecular oxygen and atomic oxygen species to create a favorable epoxidation of propylene by molecular oxygen.
文摘In the present work, we reported a novel route for the conversion of lignocellulosic biomass （sawdust） to a high-value chemical of benzoic acid under atmospheric pressure. The trans- formation involved the catalytic pyrolysis of sawdust into aromatics, the decomposition of heavier alkylaromatics to toluene, and the liquid-phase oxidation of toluene-rich aromatics to benzoic acid. The production of the desired benzoic acid from the sawdust-derived aro- matics, with the benzoic acid selectivity of 85.1 C-mol% and nearly complete conversion of toluene, was achieved using the MnO2/NHPI catalyst at 100 ℃ for 5 h. The in uence of adding methanol on the catalytic conversion of sawdust to the core intermediate of toluene was also investigated in detail.
基金Supported by the National Natural Science Foundation of China （No.20576117）
文摘Cationic ring opening polymerization of octamethylcyclotetrasiloxane （Da） initiated by acid treated bentonite was investigated. The experimental conditions were chosen on the basis of preliminary experiments.Higher temperature was found beneficial for the reaction process while stirring intensity beyond a certain level showed no obvious effect on the reaction rate. Polymers were characterized by Fourier transform infrared, proton nuclear magnetic resonance （IH-NMR） and gel perneation chromotography. The width of molecular mass distribution was found ranging between 1.2 and 1.4, which is extraordinarlly narrow compared with that of cationic polymerizations reported elsewhere （〉 1.9）. The results were believed due to the absence of free proton and counter ion which simplifies the polymerization process and the huge steric hindrance provided by bentonite particles which keeps the propagation of polysiloxane onto the surface of bentonite particles in a much more regular way. A feasible mechanism is proposed and seems to be supported well by experiments. Additionally, from the results of α, ω-dihydrogen terminated polysiloxanes prepared, the possibility of applying this potential environmentally friendly heterogeneous catalyst in industrial polymerization of cyclosiloxanes is anticipated.
基金supported by State Key Program of the National Natural Science Foundation of China(21733002)the National Natural Science Foundation of China(U1462120,21403027)Cheung Kong Scholars Programme of China(T2015036)~~
文摘Oxidative dehydrogenation of light alkanes to alkenes is an attractive alternative route for industrial direct dehydrogenation because of favorable thermodynamic and kinetic characteristics,but encounters difficulties in selectivity control for alkenes because of over-oxidation reactions that produce a substantial amount of undesired carbon oxides.Recent progress has revealed that boron nitride is a highly promising catalyst in the oxidative dehydrogenation of light alkanes because of its superior selectivity for and high productivity of light alkenes,negligible formation of CO2,and remarkable catalyst stability.From this viewpoint,recent works on boron nitride in the oxidative dehydrogenations of ethane,propane,butane,and ethylbenzene are reviewed,and the emphasis of this viewpoint is placed on discussing the catalytic origin of boron nitride in oxidative dehydrogenation reactions.After analyzing recent progress in the use of boron nitride for oxidative dehydrogenation reactions and finding much new evidence,we conclude that pure boron nitride is catalytically inert,and an activation period is required under the reaction conditions;this process is accompanied by an oxygen functionalization at the edge of boron nitride;the B-O species themselves have no catalytic activity in C-H cleavage,and the B-OH groups,with the assistance of molecular oxygen,play the key role in triggering the oxidative dehydrogenation of propane;the dissociative adsorption of molecular oxygen is involved in the reaction process;and a straightforward strategy for preparing an active boron nitride catalyst with hydroxyl groups at the edges can efficiently enhance the catalytic efficacy.A new redox reaction cycle based on the B-OH sites is also proposed.Furthermore,as this is a novel catalytic system,there is an urgent need to develop new methods to optimize the catalytic performances,clarify the catalytic function of boron species in the alkane ODH reactions,and disclose the reaction mechanism under realistic reaction conditions.
基金supported by the National Natural Science Foundation of China(91434101,91745108)the Ministry of Science and Technology of the People’s Republic of China(2017YFB0702900)~~
文摘A series of hexadecylphosphate acid(HDPA) terminated mixed-oxide nanoparticles have been investigated to catalyze the oxidation of toluene exclusive to benzaldehyde under mild conditions in an emulsion of toluene/water with the catalysts as stabilizers. With the HDPA-Fe2 O3/Al2 O3 as the basic catalyst, a series of transition metals, such as Mn, Co, Ni, Cu, Cr, Mo, V, and Ti, was respectively doped to the basic catalyst to modify the performance of the catalytic system, in expectation of influencing the mobility of the lattice oxygen species in the oxide catalysts. Under normally working conditions of the catalytic system, the nanoparticles of catalysts located themselves at the interface between the oil and water phases, constituting the Pickering emulsion. Both the doped iron oxide and its surface adsorbed hexadecylphosphate molecules were essential to the catalytic system for excellent performances with high toluene conversions as well as the exclusive selectivity to benzaldehyde. Under optimal conditions, ~83% of toluene conversion and >99% selectivity to benzaldehyde were obtained, using molecular oxygen as oxidant and HDPA-(Fe2 O3-Ni O)/Al2 O3 as the catalyst. This process is green and low cost to produce high quality benzaldehyde from O2 oxidation of toluene.
文摘Transformation of lignin into high-value chemicals is hampered by the complexity of monomers obtained from lignin depolymerization. Here we report a strategy, composed of hy-dro-demethoxylation and de-alkylation reactions, that is able to chemically converge various lig-nin-derived phenolic monomers into phenol in a single-step. Using 2-methoxy-4-propylphenol as a model compound, Pt/C exhibited the best performance in hydro-demethoxylation reaction afford-ing 80% 4-propylphenol from 2-methoxy-4-propylphenol, while H-ZSM-5 was identified as the most suitable catalyst for de-alkylation, achieving 83% yield of phenol from 4-propylphenol. Since the two catalysts operate under compatible conditions, combining the two catalysts to simultane-ously promote both hydro-demethoxylation and de-alkylation reactions was achieved. Configura-tion of how to organize the catalysts is a critical parameter, where the physical mixture of the two was most effective, providing over 60% phenol from 2-methoxy-4-propylphenol in a single-step.
基金supported by the National Natural Science Foundation of China(21373248,21673260,21133011)~~
文摘A series of novel cobalt carbonyl ionic liquids based on1,1,3,3‐tetra‐alkyl‐guanidine,such as[1,1‐dimethyl‐3,3‐diethylguanidinium][Co(CO)4](3a),[1,1‐dimethyl‐3,3‐dibutylguanidinium][Co(CO)4](3b),[1,1‐dimethyl‐3,3‐tetramethyleneguanidinium][Co(CO)4](3c),and[1,1‐dimethyl‐3,3‐pentamethyleneguanidinium][Co(CO)4](3d),were synthesized in good yields and were also characterized using infrared spectroscopy,ultraviolet‐visible spectroscopy,1H nuclear magnetic resonance(NMR)spectroscopy,13C NMR spectroscopy,high‐resolution mass spectrometry,differential scanning calorimetry,and thermogravimetric analysis.The four compounds exhibited high thermal and chemical stability.In addition,the catalytic performance of these compounds was investigated in the carbonylation of epoxides,with3a exhibiting the best catalytic activity without the aid of a base as the additive.The catalyst could be reused at least six times without significant decreases of the selectivity or conversion rate.Moreover,the catalyst system exhibited good tolerance with terminal epoxides bearing alkyl,alkenyl,aryl,alkoxy,and chloromethyl functional groups.
文摘A modified solution-diffusion model was established based on Flory-Huggins thermodynamic theory and Fujita's free volume theory. This model was used for description of the mass transfer of removal benzene from dilute aqueous solutions through polydimethylsiloxane (PDMS) membranes. The effect of component concentration on the interaction parameter between components, that of the polymer membrane on the selectivity to benzene, and that of feed concentration and temperature on the permeation flux and separation factor of benzene/water through PDMS membranes were investigated. Calculated pervaporation fluxes of benzene and water were compared with the experimental results and were in good agreement with the experimental data.
基金Supported by National Natural Science Foundation of China and National Key Technologies R and D Program of the 11th five-year plan,No.2009ZX09501-015
文摘AIM： To evaluate the hepatoprotective roles of （Z）- 5-（4-methoxybenzylidene）thiazolidine-2,4-dione （SKLB010） against carbon tetrachloride （CCI4）-induced acute and chronic liver injury and its underlying mecha- nisms of action.
